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Tellurium Precursor for Nanocrystal Synthesis: Tris(dimethylamino)phosphine Telluride
摘要： Preparations of CdTe quantum platelets, magic-size (CdTe)13 nanoclusters, and CdTe quantum wires are described using (Me2N)3PTe (with (Me2N)3P) as a Te precursor. The (Me2N)3PTe/(Me2N)3P precursor mixture is shown to be more reactive than mixtures of trialkylphosphine tellurides and the corresponding trialkylphosphines, R3PTe/R3P, which are commonly employed in nanocrystal syntheses. For syntheses conducted in primary amine solvents, (Me2N)3PTe and (Me2N)3P undergo a transamination reaction, affording (Me2N)x(RHN)3?xPTe and (Me2N)x(RHN)3?xP (R = n-octyl or oleyl). The transaminated (Me2N)x(RHN)3?xPTe derivatives are shown to be the likely Te precursors under those conditions. The enhanced reactivities of the tris(amino)phosphine tellurides are ascribed to increased nucleophilicity due to the amino-N lone pairs.
关键词： tris(dimethylamino)phosphine telluride,tellurium precursor,CdTe quantum wires,nanocrystal synthesis,CdTe nanoplatelets,(CdTe)13
更新于2025-09-23 15:21:21
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Application of Nanostructured Tungsten Fabricated by Helium Plasma Irradiation for Photoinduced Decolorization of Methylene Blue
摘要： The dendritic nanostructure was fabricated on a surface of tungsten plate by helium plasma irradiation. The nanostructure consisting of W metal was partially oxidized to form WO3 on exposure to air, and the resulting surface exhibited a broad photoabsorption in the range from 1 to 5 eV. We examined photoinduced reaction of methylene blue (MB) on the material. It was found that the partially and fully oxidized surface nanostructures were able to promote a decolorization of MB under photoirradiation even with the near-infrared light (< 1:55 eV), whose energy is lower than the band gap of WO3. The reaction rate was varied with the fraction of W and WO3 on the surface layers, that is, the partially oxidized sample promoted the reaction at a higher rate than the fully oxidized one. It is also found that the reaction rate decreased with time, which would be caused by the products accumulation on the surface and the surface oxidation.
关键词： Scanning electron microscopy (SEM),Tungsten oxide,Surface photochemistry,Plasma processing,Nano-wires, quantum wires, and nanotubes,Visible/ultraviolet absorption spectroscopy, X-ray photoelectron spectroscopy
更新于2025-09-23 15:21:01
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: From quantum dots to bulk crystals and additional boundary conditions for Rydberg exciton-polaritons
摘要： We propose schemes for calculation of optical functions of a semiconductor with Rydberg excitons for a wide interval of dimensions. We have started with a zero-dimensional structure (quantum dot), then going to one-dimensional (quantum wire), two-dimensional (quantum wells and wide quantum wells), and ?nally three-dimensional bulk crystals; our analytical ?ndings are illustrated numerically, showing an agreement with available experimental data. Calculations including exciton-polaritons are performed; the case of a large number of polariton branches is discussed, and obtained theoretical absorption spectra show good agreement with experimental data.
关键词： quantum wells,bulk crystals,exciton-polaritons,quantum wires,Rydberg excitons,quantum dots
更新于2025-09-23 15:21:01
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Nonlinear optical rectification and electronic structure in asymmetric coupled quantum wires
摘要： Asymmetric coupled quantum wires provide the possibility for realizing obvious nonlinear optical rectification due to breaking the inversion symmetry. Here, we investigated nonlinear optical rectification (NOR) and electronic states in asymmetric coupled quantum wires (ACQWs). We find that the NOR max value of the ACQWs exhibits double peak structure with the increase of the geometrical asymmetry (i.e. the left wire radius deviating from the right wire radius), thus offering a direction for achieving remarkable NORS. In the double peak structure, the max value is one to two orders of magnitude larger than the min value. Furthermore, we find that the tunneling effect with respect to the ground state is reduced with the increase of the geometrical asymmetry, while the tunneling effect with respect to the first-excited state is firstly reduced, subsequently enhanced and then reduced with the increase of the geometrical asymmetry. Such coupling pictures elucidate the double peak structure in the NOR max value of the ACQWs. Our work enriches our understanding for the NOR and quantum states of the ACQWs, thereby laying the groundwork for the design and optimization of nonlinear nano-optical devices based on asymmetric coupled quantum wires such as THz radiation sources and infrared photo-detectors.
关键词： Asymmetric coupled quantum wires,Electronic structure,Nonlinear optical rectification
更新于2025-09-23 15:19:57
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The fundamentals of harnessing the magneto-optics of quantum wires for designing optical amplifiers: Formalism
摘要： Quantum wires occupy a unique status among the semiconducting nanostructures with reduced dimensionality, no other system seems to have engaged researchers with as many appealing features to pursue. This paper aims at a core issue related with the magnetoplasmon excitations in the quantum wires characterized by the confining harmonic potential and subjected to a longitudinal electric field and a perpendicular magnetic field in the symmetric gauge. Despite the substantive complexity, we obtain the exact analytical expressions for the eigenfunction and eigenenergy, using the scheme of ladder operators, which fundamentally characterize the quantal system. Crucial to this inquiry is an intersubband collective excitation that evolves into a magnetoroton — above a threshold value of magnetic field — which observes a negative group velocity between the maxon and the roton. The evidence of negative group velocity implies anomalous dispersion in a gain medium with the population inversion that forms the basis for the lasing action of lasers. Thus, the technological pathway that unfolds is the route to devices exploiting the magnetoroton features for designing the novel optical amplifiers at nanoscale and hence paving the way to a new generation of lasers.
关键词： magnetorotons,Quantum wires,magnetoplasmons,optical amplifiers,nanoscale lasers,quantum optics
更新于2025-09-19 17:15:36
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A High-Performance InAs/GaSb Core-Shell Nanowire Line-Tunneling TFET: An Atomistic Mode-Space NEGF Study
摘要： Using a tight-binding mode-space NEGF technique, we explore the essential physics, design and performance potential of the III-V core-shell (CS) nanowire (NW) heterojunction TFET. The CS TFET “line-tunneling” current increases significantly with the core diameter dC and outperforms the best III-V axial “point-tunneling” NW heterojunction TFET ION by up to 6× for dC = 6.6 nm. Reaching such a high level of current at low supply voltage, however, requires and involves specific and sometime unanticipated optimizations and physics that are thoroughly investigated here. In spite of the commonly accepted view, we also show and explain the weak gate-length dependency observed for the line-tunneling current in a III-V TFET. We further investigate the effect of electron-phonon scattering and discrete dopant impurity band tails on optimized CS NW TFETs. Including those non-idealities, the CS-TFET inverter performance significantly outperforms that of the axial TFETs. The low-power (LP) VDD = 0.35V CS-inverter delay is comparable to that of the high-performance (HP) Si CMOS using VDD = 0.55V, which shows promise for a LP TFET technology with HP speed.
关键词： Semiconductor device modeling,Quantum effect semiconductor devices,Semiconductor heterojunctions,Tunnel transistors,Quantum wires,Quantum theory
更新于2025-09-10 09:29:36